Was just reading a post on the attenuation thread about step mashing. I have been doing step mashes for my pilsners & hefes but I wonder if the logic applies to all beers.

Is step mashing like a water profile? Style dependent?

Some do not even believe step mashes do anything. The problem in the homebrew environment is that the margin for error and tolerance is prety high. I respect the German scientific approach to brewing which makes me a step masher, but I single infuse my bitters.

I think modern malts are sufficiently adaptable that it's possible to brew beer with them many different ways. So in a sense how you mash can be dependent on the styles you brew, but also on the ingredients you use and the equipment you brew on.

My system allows for a lot of flexibility. It's a manual HERMS and I can also directly heat the mash tun. So I do tend to step mash almost all of my beers to some extent. I vary the strike temperature depending on the recipe. If there is a lot of wheat or unmalted ingredients, I like a brief protein rest at 120-125 F. For many "ordinary" beers with two-row pale North American or British malt, I will mash in at 135 F, briefly check and adjust the pH, and then raise the temperature to whatever I want for conversion. For many recipes that use pilsner malt, I mash in at 140 F and then raise it to 156-158, varying the rest times with the desired degree of attenuation I am seeking. For almost all of my beers I employ a 10-minute mashout at 168-170 F, which makes for a very easy sparge.

Is this the best way to brew? It's very hard to know because the effects are both complex and subtle. I will say that it seems to suit my ingredients and my equipment, and I'm reasonably happy with the results. However, I know other very good brewers who do it differently and manage to equal or exceed me in terms of beer quality. So my conclusion is that it's possible to brew many different ways if you adjust your ingredients and techniques. This is underscored by the great variety of commercial breweries that use rather different equipment and sometimes different ingredients to achieve generally excellent beer.

I tend to step mash all my beers. I have manual RIMS system with a direct-fired mash tun that allows me to ramp up at slightly less than 1 degree F per minute, so it's easy for me to do.

I mash in at lower temperatures so that the more heat-labile enzymes are not denatured prior to having a substrate on which to work. Enzymes such as beta-glucanase, beta-amylase, and the group collectively known as "limit dextrinase" are somewhat fragile. Lower temperatures allow them to function longer in their respective roles.

Let's look at the starch-degrading enzymes. Starch is not available to the enzymes until it is gelatinized - that is, released into solution as free molecules. In barley, starch molecules are bound up in discrete spherical granules that are highly ordered and highly water-resistant. The granules are similar to hailstones in that they are grown by layering. Heat is required to allow water to ingress the granule and to begin to dissolve it. More heat leads to faster gelatinization, but more heat also leads to faster denaturing of fragile enzymes. If the enzymes have lost functionality when the amylose and amylopectin molecules are freed from the granules, the starch will not be degraded or will be less completely degraded than would have been possible had the enzymes been preserved. Alpha-amylase is tough and will survive high-temperature infusion mashes, but it is an endogenous enzyme that randomly breaks chunks of various sizes from the starch molecules, resulting in lots of dextrins and relatively fewer fermentable saccharides. Allowing the full group of amylolytic enzymes to work together will result in far better degradation of the starch into fermentable fractions. This takes time at temperatures that will not denature the enzymes.

Barley is high in beta-glucan, and degrading it will tend to lessen the body of the beer while arguably increasing its nutritional value. The beta-glucanases tend to function best in the range that many homebrewers mistakenly call the "protein rest", but they remain active for a period of time even at 140F (which is one reason I choose to mash in there for most beers.) The beta-glucanases can play a significant role in mouthfeel and body.

The proteases are of only minor importance in the mash, as most of their work has already been done in the malt house. Kilning tends to denature most of them, and though there is minor proteolysis that occurs well into the higher temperature ranges, strictly speaking, the term "protein rest" is an oft-repeated misnomer.

So what does all this mean? Must you step mash to produce excellent beer? Of course not. As Bill said, many factors come into play in making that decision, most importantly the design of the brewhouse and secondarily, the nature of the ingredients. Can you brew virtually any style either way? Yes you can, excepting ingredients that must be cereal mashed, which is a whole different procedure that is not relevant to our discussion here.

I will tell you that anecdotally, since I started brewing this way, I have noticed that my beers are consistently clearer and cleaner than either average homebrews or my prior single-infusion efforts. They have excellent head formation and retention across a broad range of styles. They are not thin or watery - quite the opposite, in fact. In short, I think adopting step mashing as SOP in my brewery has improved my beers considerably, and I think there are scientific reasons for this to be true. As usual, YMMV.

Thanks for the great information. My research on this topic has lead me to certain mash routines for certain beers. Bascially a "hoch-kurz" mash approach thanks to Kai T. I would appreciate your input:

Hefeweizen: 20 min @ 111f 30 min @ 145f 30 min @ 158-160f

Pils: 20 min @ 133f 30 min @ 145f 30 min @ 158-160f

Ales - This is where I wonder, will a step mash make a beer that has less "British-ness" compared to a traditional single infusion? Probably not enough to notice.

I mash in a cooler and three steps is about the maximum I can do. The jump from 145f to 160f is the tough one as the volume of water at 145f in the mash wants to retain its temp.

This routine is not that difficult and does not draw out my brewday at all since the mash times are the same. The grain does not create dough balls at the lower temperatures as well which helps the whole process.

The reason for the low temperature rest in the hefeweizen is to free more ferulic acid so that you'll have more clove flavor. Ferulic acid is attached to a side chain of arabinoxylan, a structural non-starch polysaccharide that is predominate in wheat. The enzymes that free it operate at lower temperatures.

The lower temperature rests for the pilsner are designed to produce a clearer, drier product. Light body and a dry finish are critical to brewing the German Pilsner style correctly.

There's a fair amount of latitude in mash thickness, so step mashing in a cooler is possible, provided it is large enough to contain the thin mash that results if a mashout is employed. Mashing in as thick as 1.0 quarts of water per pound of grain is possible, and mashes as thin as 2.0 quarts per pound or even a little thinner will still convert well.

The jury is out about step mashing with British pale malts. I think it would make for an interesting experiment.

The answers to the above questions depend on how you define "conversion". At what point in the degradation of starch is it truly "converted"? The iodine test is really quite a crude and inaccurate measure of total starch degradation, as the color change that takes place occurs as a result of sequestration of the iodine molecules within what is known as a "clathrate", a helical "cage" similar in shape to DNA. These helices are formed by lengths of amylose. If amylose is still present, then the starch is... anyone? Anyone? NOT fully degraded! What the test is indicating is that lengths of amylose have been liberated from the vastly larger amylopectin molecules, so now the mix of molecules contains a proportionately larger number of amylose (straight) molecules versus amylopectin (highly-branched) molecules. So while a color change indicates that the starch is technically converted, it is nowhere near being fully degraded.

I would take issue with the claim that "most conversion takes place in the first 15 min of a mash". As I indicated above, it takes time to even gelatinize the starch to make it available to the enzymes, and until gelatinization occurs, there isn't going to be any conversion. If you mash in so hot as to quickly denature the lower-temperature enzymes, you will still get "conversion" if you define it as a reduction of amylopectin into poly- and oligosaccharides, but you will get incomplete reduction of the starch into fermentable fractions.

Now, to your specific questions:

Since modern malts convert so well, and also seeming rather quickly, how important is step length? That depends on the temperature and what it is that you are trying to accomplish. The gelatinization range for barley starch is listed by one source as 51-60C, or 125-140F. A rest below this will do little in the way of starch degradation no matter how long you rest. This is why a mash-in of, say, 140F makes sense, because it is at the top end of the minimum gelatinization temperature range, yet still cool enough that it doesn't immediately denature most of the enzymes. A long rest at 140F will result in more complete degradation of the starch, with the tradeoff being a reduction in the size and number of dextrins left in the beer. So longer and lower means a drier finish and somewhat less body, which may not be desirable in all styles. (You can fully convert your base malt, which is always desirable, and still have significant body and flavor through careful selection of specialty malts.)

If one holds a step too long will the malt be sort of 'converted out' by the time the next step is employed? No. You can't even get 100% gelatinization without using a pressure cooker. There will always be more starch available at normal mash temperatures. That said, your time is valuable. At some point you certainly reach a point of dimishing returns on your investment of time. Very long mid-temperature rests also introduce issues of leaching of undesirable compounds from the grist, potential thermophilic bacterial spoilage, etc. I don't see any need to go beyond 30-40 minutes at any step. (My typical mash is around 90 minutes.)

Graham provides very good information here. I will mention that too long a protein rest in the area of 122 F, while it does not gelatinize the starches, can degrade proteins to the point where heading is affected. In general I wouldn't recommend such a protein rest longer than 15 minutes.

David, I can thank Kansas State's Food Science department for a good bit of this, and the body of knowledge in brewing literature, to include UC-Berkeley's brewing texts, for the rest. (I'm in a somewhat unique position to synthesize the two. )

For a typical pale ale or IPA, I'd mash in at 140F and rest there for 20-30 minutes. I'd ramp up to 158, which would take about 30 more minutes. Then I'd rest there for 30 minutes or so. You can visually assess where you're at just by looking at the clarity of the wort in the mash tun and adjust accordingly.

For a drier style such as a German Pilsner or a Belgian Tripel, I might consider mashing in at 131F and holding there for about 15 minutes. I'd ramp from there to 140-145F and rest for 20-30, then ramp to 158 for another 30.

For a more full-bodied style like a Doppelbock or a Strong Scotch Ale, I'd first use a high proportion of Munich- or Mild-type malt(s) with locked-in body. Then I'd mash in at 140F and hold there for maybe 20 minutes, no more than 30. Then I'd ramp to 158F for probably 40.

My philosophy, again with diminishing returns in mind, is that the overall length of the mash will always be about 90 minutes. The variation will be how long I hang in the low temperatures versus the high temperatures.

I again want to emphasize that I'm not saying this is what one must do to brew great beer. I do think, however, that it offers a means of fine-tuning the beer that single-infusion just can't match.

My understanding is that while many commercial breweries employ step mashing, there are also many that do not. Now I realize that not every aspect of commercial brewing applies to homebrewing, but it is also true that many commercial breweries achieve excellent conversion and high efficiency, so I think there is something to be learned here. I'd love to know more about how those breweries who do single infusion mashing accomplish this. I know to some extent it's equipment-related, but my understanding is a lot less complete than I'd like.

David, it's not that I have any scientific or philosophical objection to a mashout - I simply run out of patience by that point. I tend to do a pseudo-fly sparge with about 170-180F water in the hopes of raising the average temperature of the wort that is drawn off from the mash to about 165-170. It's a little more complicated than that, in that I tend to vigorously stir my mash and then briefly recirculate before each step, all of which takes additional time and effort, but the short version is, "No, I do not."